The United State Department of Agriculture Forest Service manages over 192 million acres of land. Of the 1,311 threatened and endangered species listed under the USA Endangered Species Act, approximately 425 rare species can be found within National Forest or Grasslands. The Threatened, Endangered, and Sensitive (TES) Species Program is the Forest Service program dedicated to the conservation and recovery of these species. The protection, monitoring, management, and study of these species is a challenge due to landscape, bureaucratic, and financial issues. Nonetheless, researchers and volunteers are assisting with these activities for rare species. The Midewin National Tallgrass Prairie (MNTP), Will County Illinois USA, has a total of 13 TES plant species. This site will be used as a case study to demonstrate how the combined efforts of researchers and volunteers can generate data to assist with the development of management plans for rare species. In this talk the efforts of volunteers and researchers at MNTP will be discussed. Four areas will be highlighted: 1) the Plants of Concern (POC) volunteer program of Chicago Wilderness implemented through the Chicago Botanic Garden, 2) how the efforts of POC to gather plant reproductive data have benefited MNTP, 3) the research being done on the reproductive biology of two rare plants (Agalinis auriculata [Orobanchaceae] and Rudbeckia fulgida var. sullivantii [Asteraceae]), and 4) how these research efforts in conjunction with POC data have resulted in a better understanding of how biological/ecological factors and management practices have affected the reproductive biology of these rare species at MNTP. The ultimate goal of these efforts is to develop the best ex situ and in situ management programs for these rare species at MNTP.